1. Field of Invention
This invention relates generally to a mechanism for shifting the automatic transmission of an automotive vehicle, and more specifically, to a method that allows the operator to manually shift the automatic transmission.
2. Description of Prior Art
The two main components of the powertrain of an automotive vehicle are the engine and the transmission. The transmission converts engine speed and torque in accordance with the traction demand of the vehicle. Transmissions are generally either manually or automatically actuated. Manual transmissions generally include mechanical mechanisms for coupling rotating gears to produce different ratio outputs to drive the wheels. Automatic transmissions are designed to take automatic control of the frictional units, gear ratio selection and gear shifting.
The operation of an automatic transmission is typically transparent to the operator, requiring little attention from the operator. However, some operators may like more control of the vehicle in certain situations. To these operators, manual shifting of the automatic transmission is a welcome option.
Various methods have been invented to allow the operator to manually generate commands or requests for controlling the shifting of an automatic transmission. U.S. patent Ser. No. JP61/248,947 to Hideji discloses a range selector that makes available all the individual Forward gears, the Reverse gear, the Neutral position, the Park position, and the Drive position. The transmission is automatic only when the selector is in Drive, in which position the transmission automatically shifts through the Forward drive gears. With this type of system, the operator has the option to command any of the Forward drive gears, regardless of the vehicle speed. This kind of direct control causes a safety concern because it may make the engine rotate too fast or too slow.
Because of the safety concern, methods that generate sequential shift requests are more useful. With these methods, each time the operator wants to intervene in the shifting of the automatic transmission, he or she can generate an upshift or downshift request to the transmission control system. The transmission will then shift by one gear in the requested direction if the control logic allows such a shift. If the transmission is currently in gear 2 and the operator wants to manually shift the transmission to gear 4, he or she has to generate two upshift requests in order to achieve a transmission shift in a sequence from gear 2 to gear 3 and then from gear 3 to gear 4.
A number of methods have been invented for the operator to generate sequential shift requests. All of them achieve the purpose by using electric switches. The switches are incorporated into the gear range selector (For example, U.S. Pat. No. 6,053,066 to Ishii, et al., U.S. Pat. No. 6,223,112 to Nishino), the steering wheel (For example, U.S. Pat. No. 5,335,743 Gillbrand, et al., U.S. Pat. No. 5,365,803 to Kelley, et al., U.S. Pat. No. 6,053,066 to Ishii, et al., U.S. Pat. No. 6,223,112 to Nishino, U.S. Pat. No. 6,474,187 to Vollmar, U.S. Pat. No. 7,131,347 to Yoshikawa, et al.), or the steering column (For example, U.S. Pat. No. 5,865,705 to Shamoto, et al., U.S. Pat. No. 6,945,132 to Kim). These switched are operated in the form of a handle, push buttons, or a lever.
All of the existing methods for manually shifting an automatic transmission place a burden on the operator: the operator is required to use a hand to locate and manipulate an operating device (a handle, a push button, or a lever) every time he or she generates a shift request. In addition, the input device, whether it is a redesigned gear range selector, a set of push buttons on the steering wheel, or a level assembly on the steering column, may incur substantial manufacturing cost.
The rate of the movement of the accelerator pedal has been used for controlling automatic transmission. U.S. Pat. No. 5,123,301 to Hagele disclosed a method that uses that kind of information to switch between two modes of transmission operation. U.S. Pat. No. 6,213,916 to Ning prescribes a method that uses the pedal movement rate information to control the clutch engagement rate. However, no prior art has taught how to use the accelerator pedal to manually shift an automatic transmission.